Fair Value Measurements - Valuation techniques and significant unobservable inputs used in recurring Level 3 fair value measurements of assets and liabilities (Details) $ in Thousands	Jun. 30, 2023 USD ($) item	Dec. 31, 2022 USD ($) item
Fair Value Measurements
Fair Value | $	$ 479,613	$ 502,980
Loans at fair value where valuation (unadjusted) is obtained from third-party pricing service or broker quote | $	1,001	2,257
2026 Notes
Fair Value Measurements
Estimated fair value of notes | $	117,469	116,995
Senior Secured Loans | Discounted cash flow | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 267,094	$ 276,433
Senior Secured Loans | Discounted cash flow | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.100	0.093
Senior Secured Loans | Discounted cash flow | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.045	0.038
Senior Secured Loans | Discounted cash flow | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.200	0.186
Senior Secured Loans | Discounted cash flow | EBITDA Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.131	0.124
Senior Secured Loans | Discounted cash flow | EBITDA Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.094	0.087
Senior Secured Loans | Discounted cash flow | EBITDA Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.275	0.223
Senior Secured Loans | Discounted cash flow | Revenue Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.117	0.134
Senior Secured Loans | Discounted cash flow | Revenue Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.106	0.100
Senior Secured Loans | Discounted cash flow | Revenue Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.170	0.220
Senior Secured Loans | Discounted cash flow | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 107,262	$ 130,199
Senior Secured Loans | Discounted cash flow | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.055	0.044
Senior Secured Loans | Discounted cash flow | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.013	0.002
Senior Secured Loans | Discounted cash flow | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.115	0.123
Senior Secured Loans | Enterprise value | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 3,513	$ 80
Senior Secured Loans | Enterprise value | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.123	0.080
Senior Secured Loans | Enterprise value | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.048	0.080
Senior Secured Loans | Enterprise value | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.125	0.080
Senior Secured Loans | Enterprise value | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 6,864	$ 5,706
Senior Secured Loans | Enterprise value | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.023	0.025
Senior Secured Loans | Enterprise value | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.008	0.025
Senior Secured Loans | Enterprise value | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.024	0.025
Senior Secured Loans | Enterprise value | Book value multiples
Fair Value Measurements
Fair Value | $	$ 19,264	$ 19,546
Senior Secured Loans | Enterprise value | Book value multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.013	0.012
Senior Secured Loans | Enterprise value | Book value multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.013	0.012
Senior Secured Loans | Enterprise value | Book value multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.013	0.012
Senior Secured Loans | Liquidation | Probability weighting of alternative outcomes
Fair Value Measurements
Fair Value | $	$ 11,295	$ 1,488
Senior Secured Loans | Liquidation | Probability weighting of alternative outcomes | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.250	0.713
Senior Secured Loans | Liquidation | Probability weighting of alternative outcomes | Minimum
Fair Value Measurements
Investments, measurement input	0.180	0.291
Senior Secured Loans | Liquidation | Probability weighting of alternative outcomes | Maximum
Fair Value Measurements
Investments, measurement input	1.000	1.000
Unitranche Secured Loans | Discounted cash flow | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 9,712	$ 17,019
Unitranche Secured Loans | Discounted cash flow | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.090	0.088
Unitranche Secured Loans | Discounted cash flow | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.090	0.088
Unitranche Secured Loans | Discounted cash flow | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.090	0.088
Unitranche Secured Loans | Discounted cash flow | EBITDA Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.130	0.112
Unitranche Secured Loans | Discounted cash flow | EBITDA Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.128	0.091
Unitranche Secured Loans | Discounted cash flow | EBITDA Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.130	0.130
Unitranche Secured Loans | Discounted cash flow | Revenue Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.124	0.119
Unitranche Secured Loans | Discounted cash flow | Revenue Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.121	0.116
Unitranche Secured Loans | Discounted cash flow | Revenue Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.126	0.121
Unitranche Secured Loans | Discounted cash flow | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 3,688	$ 3,614
Unitranche Secured Loans | Discounted cash flow | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.092	0.089
Unitranche Secured Loans | Discounted cash flow | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.063	0.058
Unitranche Secured Loans | Discounted cash flow | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.128	0.125
Junior Secured Loans | Discounted cash flow | Market yields
Fair Value Measurements
Fair Value | $	$ 20,109	$ 20,311
Junior Secured Loans | Discounted cash flow | Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.131	0.136
Junior Secured Loans | Discounted cash flow | Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.126	0.123
Junior Secured Loans | Discounted cash flow | Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.156	0.204
Junior Secured Loans | Discounted cash flow | Revenue Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.115
Junior Secured Loans | Discounted cash flow | Revenue Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.115
Junior Secured Loans | Discounted cash flow | Revenue Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.115
Junior Secured Loans | Discounted cash flow | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 966
Junior Secured Loans | Discounted cash flow | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.002
Junior Secured Loans | Discounted cash flow | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.002
Junior Secured Loans | Discounted cash flow | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.002
Junior Secured Loans | Enterprise value | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 2,193
Junior Secured Loans | Enterprise value | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.008
Junior Secured Loans | Enterprise value | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.008
Junior Secured Loans | Enterprise value | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.008
Junior Secured Loans | Liquidation | Probability weighting of alternative outcomes
Fair Value Measurements
Fair Value | $	$ 2,039	$ 1,882
Junior Secured Loans | Liquidation | Probability weighting of alternative outcomes | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	2.447	2.258
Junior Secured Loans | Liquidation | Probability weighting of alternative outcomes | Minimum
Fair Value Measurements
Investments, measurement input	2.447	2.258
Junior Secured Loans | Liquidation | Probability weighting of alternative outcomes | Maximum
Fair Value Measurements
Investments, measurement input	2.447	2.258
Equity Securities | Discounted cash flow | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 342	$ 397
Equity Securities | Discounted cash flow | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.060	0.070
Equity Securities | Discounted cash flow | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.060	0.070
Equity Securities | Discounted cash flow | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.060	0.070
Equity Securities | Discounted cash flow | EBITDA Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.275
Equity Securities | Discounted cash flow | EBITDA Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.275
Equity Securities | Discounted cash flow | EBITDA Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.275
Equity Securities | Enterprise value | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 18,324	$ 16,630
Equity Securities | Enterprise value | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.092	0.090
Equity Securities | Enterprise value | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.045	0.038
Equity Securities | Enterprise value | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.190	0.160
Equity Securities | Enterprise value | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 4,348	$ 7,502
Equity Securities | Enterprise value | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.024	0.023
Equity Securities | Enterprise value | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.007	0.002
Equity Securities | Enterprise value | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.115	0.123
Equity Securities | Option pricing model | Volatility
Fair Value Measurements
Fair Value | $	$ 2,600	$ 2,173
Equity Securities | Option pricing model | Volatility | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.661	0.666
Equity Securities | Option pricing model | Volatility | Minimum
Fair Value Measurements
Investments, measurement input	0.418	0.494
Equity Securities | Option pricing model | Volatility | Maximum
Fair Value Measurements
Investments, measurement input	0.725	0.700